1. Field of the Invention
This invention relates to magnetic recording materials, particularly magnetic hard discs which have much improved film properties and magnetic characteristics.
2. Description of the Prior Art
Magnetic recording materials adapted to use in magnetic disc recording and reproducing apparatus are usually made by procedures which comprise mixing magnetic powders, binder resins and solvents, applying the resulting magnetic paint on a disc substrate, and baking the applied paint for curing. The magnetic recording material of this type is now required to have improved magnetic and mechanical performances because the recent trend toward high recording density causes the disc and magnetic heads to come closer to each other. In addition, starting and stopping operations of the apparatus under contact with the disc are at present adopted as usual practice. More particularly, the magnetic material should have good magnetic characteristics such as squareness ratio of BH loop, coersive force, residual flux density, and the like. Also, from the mechanical standpoint, it is necessary that the magnetic layer be brought to intimate contact with the substrate, be small in thickness, and be flat and lubricative on the surface thereof. In addition, the number of missing pulse errors and extra pulse errors which may be caused on the basis of both magnetic and mechanical defects of the magnetic material must be small.